Since their inception, electric motors have become more commonly used blocks in electrical, electronic, and electromechanical systems. Over time, different types of motors have been invented. Some motors have more specialized uses, while other motors, for example, the AC induction motor, have relatively widespread use in many areas.
The applications of electric motors have also evolved over time. Consequently, electric motors are now used in many areas of scientific, consumer, industrial, and medical products. Although in some applications, for example, a typical consumer-grade cooling fan, the electric motor is powered on or off, other applications entail more sophisticated control of motors. For example, the speed, torque, direction of rotation, and perhaps other attributes of motors are controlled in various applications.
To provide the capability to control various attributes of motors, motor controllers have been developed. The motor controllers usually include an electronic circuit that is used together with a power semiconductor drive circuit, such as an inverter. Different motor controllers can control different motors, such as alternating current (AC) motors or direct current (DC) motors, using techniques such as back electromotive force (back EMF) control, and field oriented control (FOC), direct space vector modulation (DSVM), pulse width modulation (PWM), etc., as persons of ordinary skill in the art understand.